3rd generation partnership project long term evolution (3GPP LTE) based on 3GPP technical specification (TS) release 8 is a promising next-generation mobile communication standard.
In a general radio communication system, even though a bandwidth between uplink and downlink is configured to be different from each other, only a single carrier is mainly considered. Based on the single carrier even in the 3rd generation partnership project long term evolution (3GPP LTE), the number of carriers configuring the uplink and the downlink each is one and the bandwidth of the uplink and the bandwidth of the downlink are generally symmetric with each other.
However, it is not easy to assign a large-bandwidth frequency, except for some regions worldwide. Therefore, as a technology for effectively using a broken small band, a spectrum aggregation technology exhibiting an effect similar to a technology of using logically large band by physically binding a plurality of bands in a frequency region has been developed.
For the spectrum aggregation, for example, even though the 3GPP LTE supports a bandwidth up to 20 MHz, the 3GPP LTE includes a technology of supporting a system bandwidth of 100 MHz using multi-carrier and assigning an asymmetric bandwidth between the uplink and the downlink.
Even though a base station supports the multi-carrier, the number of carriers supported by user equipments is generally limited. Alternatively, carriers assigned to the user equipments may be changed according to an amount of data to be transmitted.
There is a need for assigning multiple carriers more effectively.